In the fields of environments, food, medicine and forensic medicine, mass spectrometry is often used as a method for obtaining qualitative/quantitative information on trace amounts (order of ppm to ppb) of multi-components with a high sensitivity.
To ionize component molecules for analysis using the mass spectrometry, various types of ionizing means are used in accordance with chemical characteristics.
The use of electron-impact ionization provides structural information. Soft ionization methods (such as atmospheric pressure ionization, chemical ionization, and electrospray ionization) involve selective generation of ions including information about molecular weight.
Samples are analyzed for various components that are to be detected in trace amounts, with the samples containing foreign components. Examples of such samples include controlled substances (such as residual agricultural chemicals in food and antibiotics), contaminated substances (agricultural substances, chemical substances and physiologically active substances) in environments, and medicines contained in biological components. It is, however, difficult to accurately perform qualitative/quantitative analysis using the aforementioned ionization methods since the foreign components (multi-components) make an adverse effect and analysis is hindered.
For the analysis of the sample containing the multi-components, a gas chromatogram mass spectrometer or a liquid chromatogram mass spectrometer is used to separate the sample into components and subject each of the components to qualitative/quantitative analysis.
When gas chromatograph mass spectrometry and liquid chromatograph mass spectrometry are used, however, it takes much time to complete the separation, and conditions for the separation and the analysis for each component are complex. As a result, it takes approximately 30 minutes to 1 hour to complete the analysis. Thus, quick analysis of many specimens is difficult.
Meanwhile, a selective soft ionization method is used to cause a specific ion to collide with He or the like in a mass spectrometer and thereby obtain structural information (MS/MS method).
Since MS/MS method has selectivity in the transfer of charges during soft ionization (especially, ion-molecule reaction), emphasis is on a component that has a high affinity (proton affinity) for charges. It is, therefore, problematic for simultaneous analysis.
To quickly achieve the simultaneous analysis, it is necessary to simultaneously load multi-components, extract their respective components as ions, and analyze each of the components.
Soft ionization is optimal as ionizing means but the following effect occurs. From the selectivity depending on the affinity for charges, the component having a high affinity for charges is sensitized while the component having a low affinity for charges is suppressed in sensitization. Under this effect, the selectivity depending on the affinity for charges prohibits the simultaneous analysis whereas an ion-molecule reaction effectively takes place, which indicates that the efficiency of the ionization is high.
Like in a technique described in Patent Document 1, an invention has been made which provides a mass spectrometer with a plurality of ion sources each different in ionization.